This is a review and detailed measurements of the QSC DCS2422 "Digital Cinema" Power Amplifier. It is on kind loan from a member. It must be sold through specialty channel as I can't find it available much. From the bit of searching I did, it seems to go for US $550.
This digital cinema characterization applies to the connectivity of the box. Otherwise this is a normal power amplifier in rack mount configuration:
There is a nice dial with wide range of gains you can dial in. I liked the clipping indicator.
There is a speed controlled fan which is good. What is not good in home hifi situation is that even in its slowest mode there is a whine to the fan that is audible from 6 feet away. If you are going to use this amp, it would need to be in an equipment closet.
The back panel shows the locking SpeakON speaker connectors and only a pair of XLR inputs:
Given the programmable gain you can use RCA to XLR cables. I won't go through the rest of the features, selectable with dip switches.
Power Amplifier Measurements
I set a gain close to what I typically see and dialed in enough input for 5 watts of output:
As noted, channel 2 was fine but channel 1 was all over the place. Its SINAD (signal over noise and distortion) hit a low of 49 dB and a high of 83 dB (later in testing). There is some kind of instability there. I noticed that jiggling the speaker cable in that channel caused some variations too so maybe it is mostly the connector.
Channel 2 beats the THD+N spec so that is good.
Here is a warm up sequence although the unit was not at room temp before I started:
So Channel 1 even when "stabilized" still acts different from the other channel.
Using the dashboard average of the two channels, this is what we get compared to other power amps tested:
Frequency response was very good with just a bit of droop at 20 kHz:
FFT spectrum of 1 kHz tone tells us about the design of this DCA2422:
We see a spike a bit above 100 kHz. QSC does not indicate the topology of the amplifier but does say it has a switching power supply. The switching power supply substantially lowers the weight of this unit and brings high efficiency that way. I suspect the Amp is some kind of class G (multi-voltage class AB amplifier). The spikes we see are I think the switching frequency of the power supply bleeding through. They are comfortably above the audible range and unlike class D amps, at rather low levels. Overall, this is a much cleaner spectrum than I see on class D amplifiers (which use switching power supply and amplifiers).
Testing with 4 ohm load shows copious amount of power available:
We can see channel 1's worse performance just the same here. Compared to our best ever measured power amplifier using Hypex NC400, we have tons more noise and distortion. But we also have far more power at much lower cost.
I finally took the time to properly mount my dummy loads in a rack mount case with a nice switch to select between 4 and 8 ohms so here are the results of latter:
Unlike 4 ohm where we came up short, the 8 ohm measured power is actually better than the specs.
Perhaps it is best to compare the QSC to another commercial amp I have tested: the Crown XLS1502:
If QSC's Channel 1 had behaved better, it would have beat the Crown across the board. As it is, one channel is better, the other much worse. There is higher output power though (sorry the cursor is not set to read that properly from the graph).
Here is how intermodulation distortion rates at different power levels:
Fascinating how closely the QSC tracks the performance of Klipsch Powergate. It of course leaves it in the dust as far as power is concerned.
Conclusions
The QSC DCA2422 amplifier is the typical commercial power amplifier with tons and tons of power in a light and low cost enclosure. Unlike class D competitors, it seems to have a much more stable design. The issue with it is the one channel misbehaving. If that is typical of the rest of the production, then that is not good. If it is just an issue with this specific sample, then this is a good buy for a rack-mount install to drive subwoofers and such. The fan noise rules it out for any kind of "domestic" application.
------------
As always, questions, comments, recommendations, etc. are welcome.
In the process of crimping a bunch of connectors to build my dummy load, I realized how tough the ratchet style crimping tools are on high-quality yellow ring connectors. Searching for a power version, I found this wonderful tool:
Bad news is that as most things good in life, it costs money, lots of money! $500 to be exact. So Please help fund that by donating generously using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
This digital cinema characterization applies to the connectivity of the box. Otherwise this is a normal power amplifier in rack mount configuration:
There is a nice dial with wide range of gains you can dial in. I liked the clipping indicator.
There is a speed controlled fan which is good. What is not good in home hifi situation is that even in its slowest mode there is a whine to the fan that is audible from 6 feet away. If you are going to use this amp, it would need to be in an equipment closet.
The back panel shows the locking SpeakON speaker connectors and only a pair of XLR inputs:
Given the programmable gain you can use RCA to XLR cables. I won't go through the rest of the features, selectable with dip switches.
Power Amplifier Measurements
I set a gain close to what I typically see and dialed in enough input for 5 watts of output:
As noted, channel 2 was fine but channel 1 was all over the place. Its SINAD (signal over noise and distortion) hit a low of 49 dB and a high of 83 dB (later in testing). There is some kind of instability there. I noticed that jiggling the speaker cable in that channel caused some variations too so maybe it is mostly the connector.
Channel 2 beats the THD+N spec so that is good.
Here is a warm up sequence although the unit was not at room temp before I started:
So Channel 1 even when "stabilized" still acts different from the other channel.
Using the dashboard average of the two channels, this is what we get compared to other power amps tested:
Frequency response was very good with just a bit of droop at 20 kHz:
FFT spectrum of 1 kHz tone tells us about the design of this DCA2422:
We see a spike a bit above 100 kHz. QSC does not indicate the topology of the amplifier but does say it has a switching power supply. The switching power supply substantially lowers the weight of this unit and brings high efficiency that way. I suspect the Amp is some kind of class G (multi-voltage class AB amplifier). The spikes we see are I think the switching frequency of the power supply bleeding through. They are comfortably above the audible range and unlike class D amps, at rather low levels. Overall, this is a much cleaner spectrum than I see on class D amplifiers (which use switching power supply and amplifiers).
Testing with 4 ohm load shows copious amount of power available:
We can see channel 1's worse performance just the same here. Compared to our best ever measured power amplifier using Hypex NC400, we have tons more noise and distortion. But we also have far more power at much lower cost.
I finally took the time to properly mount my dummy loads in a rack mount case with a nice switch to select between 4 and 8 ohms so here are the results of latter:
Unlike 4 ohm where we came up short, the 8 ohm measured power is actually better than the specs.
Perhaps it is best to compare the QSC to another commercial amp I have tested: the Crown XLS1502:
If QSC's Channel 1 had behaved better, it would have beat the Crown across the board. As it is, one channel is better, the other much worse. There is higher output power though (sorry the cursor is not set to read that properly from the graph).
Here is how intermodulation distortion rates at different power levels:
Fascinating how closely the QSC tracks the performance of Klipsch Powergate. It of course leaves it in the dust as far as power is concerned.
Conclusions
The QSC DCA2422 amplifier is the typical commercial power amplifier with tons and tons of power in a light and low cost enclosure. Unlike class D competitors, it seems to have a much more stable design. The issue with it is the one channel misbehaving. If that is typical of the rest of the production, then that is not good. If it is just an issue with this specific sample, then this is a good buy for a rack-mount install to drive subwoofers and such. The fan noise rules it out for any kind of "domestic" application.
------------
As always, questions, comments, recommendations, etc. are welcome.
In the process of crimping a bunch of connectors to build my dummy load, I realized how tough the ratchet style crimping tools are on high-quality yellow ring connectors. Searching for a power version, I found this wonderful tool:
Bad news is that as most things good in life, it costs money, lots of money! $500 to be exact. So Please help fund that by donating generously using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).